Do these people understand that corporate/business taxes are based on profit?
They do not comprehend that high enough taxes discourages profit-making activity. They view income as a fixed given (hence the "living wage" notion, but that digresses), with no consideration that taxing a million-dollar income at 90% will persuade the worker to reduce his efforts 85% (same net income), dropping expected gov't tax revenue 95%. They think tax_rate = C x tax_revenue. They laugh at the Laffer curve.
They do not observe that Steve Jobs' salary from Apple was $1. They do not observe that Ronald Regan, as actor, did not make many more movies because doing so would put him in a 90% tax bracket. They don't comprehend that 1% of a million is greater than 50% of a thousand. And they don't notice that federal revenue NEVER exceeds 20% of GDP.